Today's automotive vehicles are required to have an onboard refueling vapor recovery (ORVR) system to prevent the discharge into the atmosphere of gasoline (hydrocarbons) vapors that are displaced during refueling of a gasoline tank. These (ORVR) systems are somewhat complex utilizing valves and diagnostic feedback to store the hydrocarbon vapors in a charcoal canister to be later burnt through operation of the engine.
However, such (ORVR) systems known to me do not capture fuel spillage, refuel nozzle fuel dripping or fuel splash back which may represent a greater environmental threat than the aforesaid hydrocarbon vapors. Many persons readily observe such fuel drippings that fall to the ground and spillage that occurs when the refueling nozzle is returned to the gas pump.
During engine operation, the intake manifold develops a vacuum that is used to operate various systems involving heating, ventilation and air conditioning (HVAC), cruise control, and brake boost assist for vehicles with power brakes. A vacuum reserve canister is directly connected via a vacuum line to the engine manifold and is then used as the vacuum source.